In various devices provided with an image acquisition device, an image processing device, etc., since the amount of data to be transmitted is increased in association with an increased number of pixels of an image acquisition element, high-speed data transmission/reception is widely performed by using optical transmission media, such as a plurality of optical fibers. Then, when a plurality of optical transmission media are connected to each other or when a plurality of optical transmission media and various optical devices are connected, optical transmission connectors for transmitting/receiving optical signals, which serve as data, are provided at a connecting portion therebetween.
Among such optical transmission connectors, various optical transmission connectors in which lenses are made to have characteristics in order to improve the data transmission efficiency by expanding the light-beam diameters of optical signals from the optical transmission media have been proposed (for example, see PTLs 1 and 2).
PTL 1 discloses an optical connector that collimates optical signals from a plurality of optical propagation paths (optical transmission media), in a lens array in which the same number of resin lenses as the optical propagation paths are arrayed, and that causes the optical signals to be emitted from the lens array to another device.
Furthermore, PTL 2 discloses an optical module in which, between an optical waveguide group having a plurality of optical transmission paths and a photoelectric element group having a plurality of photoelectric elements, a first convex lens that has an effective diameter larger than the distance between the optical axes of the two farthest optical transmission paths and a second convex lens that has an effective diameter larger than the distance between the optical axes of the two farthest photoelectric elements are provided, and optical signals from the optical waveguide group are collimated in the first convex lens and are focused on the photoelectric elements by the second convex lens.
Incidentally, optical transmission connectors are also provided at a connecting portion between a scope and an image processing device in an endoscope system. Then, because there is a fear that foreign matter, water stains, or the like will adhere to optical transmission connector portions at the time of attachment/detachment or cleaning of the scope, thus reducing the transmission efficiency, optical transmission connectors that achieve an improved transmission efficiency by using lenses such as those mentioned above are used. On the other hand, there is a strong demand for size reduction of endoscope systems from the point of view of reducing the burden on patients, and it is preferred that the optical transmission connectors to be applied to endoscope systems be small.